Scoliosis, Which is an abnormal curvature of the spine coupled with vertebral rotation, is most commonly found in adolescent females This abnormal curvature and rotation causes deformity of the rib cage witch results in asymmetries of the trunk. In a previous study (Mahood,, J. K. et al. "Perceptions of Cosmetic Deformity in Scoliosis", Proceedings of the 2nd International Symposium on Three Dimensional Scoliotic Deformities, Pescara, September, pp. 239-242, 1994), seven features of scoliosis were identified: shoulder height and shoulder angle differences, pelvis asymmetry, decompensation, waist crease, scapula height difference and waist asymmetry. These identified features account for 85% of the overall impression of trunk deformity. Further, studies have established the repeatability and reliability of measuring surface features. In other words, these seven features can be reliably measured to provide an objective score of cosmetic deformity.
Clinicians have few non-surgical treatment tools for children with potentially progressive spinal deformities such as scoliosis. Brace treatment is most commonly used despite poor compliance and much uncertainty as to effectiveness (Houghton, R, et al. "Monitoring True Brace Compliance", Proceedings of the 21st Meeting of the Scoliosis Research Society, Hamilton, Bermuda, September, p. 101, 1986; Ylikkoski, M. et al. "Biological Factors and Predictability of Bracing in Adolescent Idiopathic Scoliosis", J Pediatric Orthopedics, Vol. 9, pp. 680-683, 1989). The Boston and Charleston braces are most frequently prescribed due to their low profile. To be effective, the Boston brace is required to be worn for up to 23 hours/day. The nighttime Charleston brace (Price, C. T. et al. "Nighttime Bracing for Adolescent ldiopathic Scoliosis with the Charleston Bending Brace", Spine Vol. 15, No. 12, pp. 1294-1299, 1990) must be worn 8 hours/night. The degree of support and the extent of corrective action provided by a brace depends on the location, magnitude, and direction of the pressures exerted relative to the location of the spine (Emans, J. et al. "The Boston Brace System for Idiopathic Scoliosis--Follow-up Results in 295 Patients", Spine, Vol. 11, No. 8, pp. 792-801, 1986).
However, it has been found that the constant pressure exerted by a brace may cause permanent deformation of the rib cage or the soft tissues directly under the pressure points. Also, it is believed that the brace's action is not primarily passive via direct mechanical forces on the spine, but that its effectiveness requires the active cooperation of the patient or person, (Dworkin, B. et al. "Behavioral method for the treatment of Idiopathic Scoliosis", Proc. Natl. Acad. Sci. Vol. 82, pp. 2493-2497, 1985) i.e., the patient or person uses their own muscles to reduce the spinal curvature as she or he holds their body away from the pressure points.
Therefore, it is recognized that monitoring the posture of, and active correction of the posture, the subject or patient is a useful aid to the treatment of various musculoskeletal conditions, such as scoliosis and spinal curvature, either on its own or in conjunction with other treatment methods and devices. Specifically, treatment approaches that rely less on mechanical correction and more on providing appropriate feedback to the subject may have considerable potential.
The monitoring of a subject's or patient's posture typically requires the actual taking of repeated measurements of the features of the trunk during waking hours, using these measurements to detect postural mal-alignment and signaling to the subject that a postural correction is required. In the specific area of monitoring subjects with spinal deformities, one or more features, such as the seven features noted above, must be measured and any differences from expected values determined. In the case when more than one feature is being monitored, information from some or all the features may need to be combined to signal the need for postural improvement.
Thus, the taking of actual measurements of these features on a constant basis is often a relatively impractical and cumbersome approach to monitoring and correcting posture. As a result, attempts have been made to develop various devices for monitoring posture and providing feedback with respect to that posture so that the subject can actively correct any undesirable features of the posture.
For instances, a technique described by Schroth et al. (Lehnert, C. S. "Introduction to the three-dimensional scoliosis treatment according to Schroth", Physiotherapy, Vol. 78 No. 11 pp. 810-815, 1992; Weiss, H. R. "The Progression of Idiopathic Scoliosis under the Influence of a Physiotherapy rehabilitation Programme", Physiotherapy, Vol. 78 No. 11, pp. 815-82, 1992) called rotational breathing attempts to actively correct the body shape. The continuous muscular training results in a re-education of the scoliotic posture into a corrected balanced posture. An electronic device called the micro-straight orthosis uses behavioral principles and therapeutic theory to help correct spinal deformity as well as cosmetic appearances. This device uses chest and torso cables and a microcomputer to continuously measure the length of the spine. If the length of the spine is different from the expected value, an audible tone signals the subject every second until correct posture is attained. Thus, one drawback of this device it that it provides feedback on the measured length of the spine only.
U.S. Pat. No. 3,582,935 issued Jun. 1, 1971 to Verhaeghe is directed at a device comprised of a belt connected to a triggering plate and a spring switch arm which close an electrical circuit when they come into contact with each other. The belt is placed snugly about the waist of the subject. If the subject permits his abdominal muscles to relax and thus be distended, the trigger plate will engage the switch arm, resulting in the closing of the electrical circuit. Closure of the electrical circuit activates an audible signal cautioning the subject to tense the relaxed abdominal muscles. This device is intended to signal the subject with respect to incorrect body posture, particularly in the abdomen. However, it would appear to have limited application to other features of incorrect posture.
U.S. Pat. No. 4,730,625 issued Mar. 15, 1988 to Fraser et, al. describes an article of apparel, that is worn by a subject which includes a posture sensor. The posture sensor is comprised of an elongated strip which fits into a horizontal or vertical pocket on the back of the article of apparel. Semiconductor strain gauges are mounted at the ends of these elongated strips. When the subject moves and a strain is applied to the gauges, the gauges produce an electrical signal which is proportional to the amount of strain applied. This patent specifically teaches a system for detecting changes in posture from the normal. However, many subjects with spinal deformities or abnormalities do not have a normally symmetric trunk so it is not sufficient to monitor changes of posture in the midline of the back only. For example, the angle formed by the apices of the scapulae and the horizontal is an important trunk feature to be monitored. Because the space between these bones is concave, the apparel of this invention will bridge this area of the back and mask the true extent of this particular trunk feature.
As stated, each of these devices only monitors a single parameter aspect or feature of posture. Further, these devices only, monitor a parameter in a single dimension or plane. Therefore, these devices may not be suitable for subjects having other postural abnormalities and they may not permit the subject to correct the deficient posture or abnormal features with any degree of accuracy. This is particularly so given the interplay of the features noted above, which may act together to produce the spinal deformity actually observed.
There is therefore a need in the industry for a relatively accurate method and a device, as compared to known methods and devices, for monitoring the position or orientation of one or more objects or subjects and providing feedback with respect to the position or orientation, in any dimension and preferably in three dimensions. Further, there is a need for a relatively accurate method and a device for monitoring the posture of a subject and providing feedback with respect to the subject's posture, such as by signaling when either a desirable or undesirable posture exists, so that a desirable posture can be established.